Strep Infections May Be Associated with ADHD

From the WebMD Archives

May 12, 2000 -- In the past, some researchers have suggested there is a relationship between common strep infections and neuro-psychiatric problems, such as Tourette syndrome and obsessive-compulsive disorders. Now a Yale research team says there appears to be a much stronger relationship between strep infections and attention-deficit/hyperactivity disorders.

"Over half the children with Tourette syndrome also have ADHD," says researcher Paul Lombroso, MD. "Perhaps the group that has all three conditions may be particularly vulnerable to streptococcal infections." Lombroso is an associate professor of child psychiatry at the Yale University School of Medicine in New Haven, Conn.

The research was designed to look at the possibility that Tourette syndrome and obsessive-compulsive disorders (OCD) might be caused or aggravated by recent strep infections. "In fact, we found the clearest association was not with those conditions but with a subgroup who had ADHD," Lombroso says. "This was an unexpected finding."

Clearly, he says, more research is needed. "This is a preliminary study, so these results must be replicated and expanded."

The researchers looked at strep antibodies in about 100 people ages 7 to 55 who had OCD, Tourette syndrome, or ADHD, as well as a group of people who didn't have any of these conditions. They found that patients with ADHD had high levels of strep antibodies, suggesting a recent infection. They didn't find similar elevated levels of antibodies in people who had Tourette syndrome or OCD, but did not have ADHD.

This study looked at patients during one particular "slice of time," Lombroso says. To clarify the relationship among strep infections and childhood neuro-psychiatric disorders, researchers need to follow patients for two or three years. The Yale group has now begun such a long-term study.

"This is an interesting paper," says Mark Wolraich, MD, who reviewed the study for WebMD. He says longer-term research focusing on children who only have ADHD is needed. "The issue is certainly worth pursuing," says Wolraich, a professor of pediatrics at the Vanderbilt University School of Medicine in Nashville, Tenn.

"Sometimes things do occur which we don't expect, so we always need to be open to new ideas," says Howard Schubiner, MD, who also reviewed the study for WebMD. But he cautions that all that the researchers have found is an association in a few people. Schubiner is professor of pediatrics, internal medicine, and psychiatry at Wayne State University School of Medicine in Detroit.

Meanwhile, the study's authors caution against treating children with OCD or ADHD with antibiotics in hope of improving those conditions. Of course, if a child has a sore throat or an ear infection due to strep, antibiotics are appropriate. But the researchers say they see no point in trying to use antibiotics as a general preventative measure until we know far more about the relationship among these three conditions and strep infections.

Wolraich and Schubiner say they agree with that conclusion. "Even if ADHD did turn out to be due to an immunological reaction to a strep infection, or to any infection, antibiotic treatment would not necessarily help, since you have to treat the immune reaction, not the infection itself," Schubiner says.

The research was funded by the National Institute of Mental Health, the National Institutes of Health, and the Stanley Foundation of Muscatine, Iowa.

Vital Information:

  • A new study has shown that children with ADHD are more likely to have high levels of strep antibodies, suggesting a recent strep infection.
  • Previously, scientists had suspected that strep infections were associated with Tourette syndrome and OCD, but the new study did not find such an association.
  • Researchers caution that giving antibiotics to prevent ADHD is not a good option at this point.

To read more, visit our Diseases and Conditions ADD/ADHD page.